The joining of titanium and refractory materials such a tantalum to ferrous alloys, as well as the joining of aluminum alloys to ferrous alloys has presented significant problems in the prior art. These problems are a result of metallurgical incompatibilities, such as the limited solubilites of these materials in iron and ferrous alloys, the uncontrolled formation of intermetallic compounds, and also the rapid oxidation rates of some of the materials. These problems have prevented the development of a method for joining these materials which would be suitable for production and manufacturing purposes.
The following United States Patents comprise the prior art closest to the present invention: U.S. Pat. Nos. 3,935,417; 3,794,807; 3,463,901; 3,458,683; 3,999,030; 3,999,031, U.S. Pat. Nos. 3,808,395; 3,560,700; 3,294,951; 3,258,576; 4,063,062; 3,975,612.
The patents listed in the preceding paragraph are generally characterized as attempts in the prior art to employ electron beam or other particle acceleration welding techniques to join dissimilar metals which cannot be joined by conventional techniques. However, it is noted that none of these patents disclose the use of an accelerated particle beam to join aluminum alloys to ferrous alloys, nor to join refractory metal to ferrous alloys, as is shown by the present invention.